Suppose tomorrow, on present-day Earth, a group of scientists published a paper detailing a series of experiments conducted over the last ten years that successfully activated and deactivated the quality of life that makes a creature intelligent. The means of this technology could be a specific radio signal, manipulation of DNA, or what have you; it's not pertinent to this question.
How would general society respond to this development in both the immediate and long-term time frames? What legal and cultural ramifications would occur?
Whatever the means of controlling intelligence, assume it is easy to produce in a dedicated lab, but not trivial or inexpensive. The cost to produce this effect is roughly \$25,000 (US) (with working equipment) and can be done by a team of four scientists and one engineer. Building the necessary equipment requires four months of dedicated work, \$100,000 (US), and 5,000 sq. ft. of workspace (space for security apparatus and private power source included).
Creatures made intelligent by this process don't spontaneously start speaking human languages; they are still limited by their physical capabilities. However, their new-found intelligence does offer them the ability to learn human language as easily as the average human. When a creature is first made intelligent, it is roughly equivalent to a three-year-old human child; creatures made unintelligent revert to their previous state (ape-like for humans). Creatures with larger or more complex brains (e.g., sharks, dolphins, elephants) can achieve a higher final level of intelligence, potentially exceeding current human levels of intelligence; insects, spiders, mice, and similar small creatures barely progress beyond the initial intelligence state.
As implied above, currently-intelligent creatures (i.e., humans) and newly-intelligent creatures alike can have their intelligence turned on or off via this technology. The process requires between 4-8 hours of work, depending on the individual involved; the individual must remain still throughout the process, usually through sedation. A creature can be forced to undergo the process, typically by being sedated first.